Nanoparticles: A brighter image

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A team of French researchers from Ecole Nationale Superieure de Chimie in Paris developed nanoparticles for high-contrast biomedical imaging in the same type of long-lived luminescence that lights up street signs and brightens paints.

One application of nanoparticles — such as semiconductor quantum dots — is optical imaging in biomedicine. However, when an external light source optically excites the nanoparticles, their contribution is often washed out by fluorescence from surrounding tissue.

Quentin le Masne de Chermont, Daniel Scherman and colleagues from the Ecole National Superieure de Chimie in Paris have therefore developed long-lasting luminescent nanoparticles that can be optically excited before being injected for in vivo imaging. The nanoparticles have the composition Ca0.2Zn0.9Mg0.9Si2O6 and contain small amounts of dysprosium and manganese dopants. Once the dysprosium is optically excited, it slowly releases its energy to the manganese, which, in turn, emits red to near infra-red light.

The French group tested the biodistribution of these nanoparticles in 'Swiss' mice and found that the nanoparticles luminesce for at least an hour. Another advantage of the chosen material is that the peak fluorescence occurs at a wavelength of 690 nm, which lies in the all-important window of tissue transparency. These nanoparticles can therefore be used to image deep-tissue in small animals, such as in the hind-leg of a mouse.



Source: http://www.nature.com/nnano/reshigh/2007/0607 [..]







Story posted: 5th June 2007